7 Best Electric Tankless Water Heaters

7 Best Electric Tankless Water Heaters – (Reviews & Guide 2021)

The first storage-type hot water heater unit is believed to have been invented by Edwin Ruud, all the way back in 1889. That specific unit allowed water to be heated, as well as stored, in a metal tank until it was needed. Naturally, things have evolved, and the first iteration of the water heater is seen as inefficient and bulky. This is because the traditional tank models are limited by the amount of water that they can hold.

On top of that, we also have the fueled and electric models of tankless water heaters. Today, we’ll be taking a look at the best electric tankless water heaters. It is believed that these do not receive the credit that they deserve and are – in some cases – better than their fueled counterparts. Before introducing you to an extremely comprehensive buying guide, let’s analyze some electric tankless water heater reviews and possibly help you find the right fit for your home and needs.

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What Is an Electric Tankless Water Heater?

An electric tankless water heater is, as you may easily deduce, a water heater that runs on electricity and doesn’t need a tank to store water. Basically, it is able to provide you with hot water only when you need it.
On top of that, such heaters do not produce standby energy losses that usually come with the traditional, storage water heaters. This will, obviously, save you money.

Electric tankless water heaters start working when a hot water tap is turned on. In such a moment, cold water will travel through a pipe and into the heater’s unit. In our case, an electric element will then heat the water.

Therefore, tankless water heaters are able to deliver residents a constant supply of hot water. There is no need for you to wait for a tank to fill up with the hot water that you need.
Even though the output of a tankless water heater limits the flow rate, it goes without saying that such products have indeed changed the definition of on-demand type water heaters.

How Efficient Are Electric Tankless Water Heaters?

Reportedly, the normal thermal efficiency of an electric tankless model is around 78 to 85%. A high energy-efficient model can save you up to 60% in energy costs every single month. Of course, heating bills will also be saved to a large extent.

On top of that, it is said that tankless models use 30 to 50% less energy than the traditional tank units, mainly because they heat water only when you actually need it. It was shown that the usual family is able to save roughly $100 – or even more – on energy costs per year.

There is no doubt that electric and tankless models are efficient. First of all, the tankless models clearly have the upper hand in terms of efficiency, as the heater’s unit does not have to store the water.

On top of that, even though it’s more expensive, electricity will save you money in the long run as there’s not much of it that goes to waste. If you remember, most of the models that we reviewed used up to 98.9% of the energy that they were fed with to actively heat water.

Best Electric Tankless Water Heaters Comparison Chart

Stiebel Eltron 15 Trend Tempra, Tankless Water Heater

EcoSmart ECO 27 Electric Tankless Water Heater

Stiebel Eltron Tempra 24 Plus Whole House Tankless Electric Water Heater

Rheem RTEX-13 Residential Tankless Water Heater

EcoSmart ECO MINI 2.5 120V Electric Mini-Tank Water Heater

Rheem RTEX-24 Residential Tankless Water Heater

ECOTOUCH Electric Point-of-Use Hot Water Heater

Electric Tankless Water Heater Reviews – Top-Picks

This tankless water heater from Stiebel Eltron comes with a 4.5-star rating and with over 600 customer reviews. The body of the heater itself features a sleek design that saves spaces – since there’s no venting required.

The product also features digital displays that ensure accurate temperature delivery, as well as maximum energy efficiency. You can also make use of the pre-set temperature buttons on the Plus models of this product in order to access the temperature memory settings.

The Advanced Flow Control technology helps this product maintain hot water temperature automatically, for continuous comfort. No matter the type of water demand in your home, it is stated that your shower will always stay hot!



The second product on our list, the EcoSmart ECO 27, has a 4-star rating and more than just enough reviews, so to say. Right of the bat, the manufacturer claims that you can save up to 50% on water heating costs.
In terms of features, the heater comes with digital temperature control, in 1-degree increments, which allow you to efficiently control the hot water. The activation flow of this specific unit is 0.3 GPM.

The insides of this product are made from stainless steel and copper, ensuring durability, efficiency, as well as ease of replacement. The dimensions are 17H, 17W, and 3.625D, making the unit compact and helping you save space within your home.



Yet another Stiebel Eltron product on our list – it’s only natural, given that this manufacturer is one of the more popular when it comes to electric tankless water heaters.

This particular model comes with digital temperature control, as well as proven reliability. On top of that, the Tempra-labeled models are said to give constant energy savings as the heaters equipped with this technology are on only when you need hot water. Reportedly, they have no standby losses.

The heating chambers of the water heater are made of solid copper, to minimize heat loss, while the Advanced Flow Control technology keeps the temperature constant. This interesting piece of tech is able to slightly reduce the water flow when the hot water demand exceeds the heater’s capacity. Obviously, this will maintain the liquid’s constant temperature.



One new manufacturer entry to our list is this water heater from Rheem. This particular product features external adjustable digital thermostatic control with a LED display, with quite a high accuracy.

The power control is self-modulating and the two heating elements are based on durable copper immersion. The product is also field serviceable – so, you don’t have to worry about uninstalling it in case something goes wrong.

Moreover, the installation is pretty simple. The package comes with everything you need: a 3-feet electric cable, ½ NPT adapters included, as well as side ½ inch compression water connections. This residential tankless water heater comes with 99.8% energy efficiency and with a water-saver shower head feature that runs on 1.5 GPM.



This product from EcoSmart comes with a design fitted for its name – compact and sleek, meant to fit almost anywhere within your house.

The water heaters of the ECO MINI series are said to be 99.8% energy efficient. Judging by the number of positive reviews and by the fact that this model is Amazon’s Choice in terms of small water heaters, we can assume that to be true.

Reportedly, this water heater is pretty easy to install and doesn’t require a lot of know-how – just a little bit of intuitive knowledge. It is manufactured in the United States, has an amperage capacity of 12 A, and runs on 120V.



Yet another product from Rheem, as well as another Amazon’s Choice on our list, the RTEX-24 model features an external digital thermostatic control unit with a LED display. The product is also equipped with what is reportedly the most advanced self-modulation technology, which allows you to adjust power in order to meet the demand for hot water.

Unlike the previous Rheem product, this one comes with three heating elements based on durable copper immersion. As expected, the installation is very simple, as the bottom of the water heater features ¾ inch NPT water connections.

Furthermore, this model is also threaded, ensuring ease of replacement and installation. It has a flow rate of up to 5.9 GPM.



The last product on our list is the ECOTOUCH electric tankless water heater. Featuring a 5.5kW heating system, the unit can supply you with instant, endless, and consistent hot water of 116 F or higher.
Reportedly, you don’t need to wait for the water to preheat or to adjust it until it gets to the right type of hot.

In addition, this water heater comes with a smart self-adjustment. This means that the product will adjust its power based on the water’s flow rate and the temperature setting – all of this in real-time. When the water flow is reduced, for example, the heater will apply less power.

Because of this, you will still get the ideal water temperature without having to bear with scalding hot water.



Electric Tankless Water Heaters Buying Guide

Now, we’ve prepared for you a very comprehensive guide that will most likely help you make the right decision when it comes to buying an electric tankless water heater. If the products we’ve reviewed earlier didn’t interest you that much, then you can keep on reading and find out how you can search for a tankless water heater on your own. Therefore, without any further ado, let’s see what you should know about electric tankless water heaters.

When it comes to buying an electric tankless water heater, there are a couple of things that you should consider. However, on top of it all is understanding the hot water needs of your household. This means that you shouldn’t go for the cheapest or for the most power-hungry water heater out there, especially if you know that you either need a lot of hot water or if you live alone. Buying such appliances involves analysis and proper decision making. Pay attention to this when buying water heaters and not only!

Let’s skip to the important part and see what you should ask and consider when buying an electric tankless water heater, besides the hot water demand. Meanwhile, we will compare electric tankless water heaters to gas tankless water heaters.

It is well known that electric tankless water heaters are less expensive than their gas-powered counterparts. For example, a quality model can be bought for around $600.

However, keep in mind that there are homes that are not built to provide the water heater with the electrical requirements that it needs to operate. Installing an electric tankless water heater in such a home will increase the installation expenses – upgrading the house’s electrical system is not cheap.

Lastly, since there are no exhaust gases produced by an electric unit, you won’t have to install any venting in your home. Moreover, you can install the electric water heater wherever you want in your home!

Most electric tankless water heaters come with a rather simplistic design. Such units may not look appealing for some of you, but the fact that they are easier to troubleshoot is worth the lack of style.
In fact, you could troubleshoot, diagnose, and repair an electric tankless unit on your own. This also makes an electric unit have a longer service than a gas tankless water heater.

Electric models are also very small. As you’ve seen in our review section, they even come in mini models that can fit anywhere. Usually, electric systems are about the third the size of gas systems.

They are known to be extremely energy efficient. Most of the units we have reviewed use over 98% of the electricity they receive to heat the water. This means that no power is lost – never.

On the other hand, keep in mind that electric units do require a substantial amount of energy to operate. As mentioned above, if your home is not fit to supply this device with the power it needs, you will have to upgrade your electrical system. The very good thing about electric tankless water heaters is that these products do not produce greenhouse gases. In short, you have on-demand hot water brought to you in an environmentally friendly way.

Naturally, you will want the water heater to have a water flow big enough to satisfy all your needs. In this respect, you may choose between single-use and whole-house heaters.

A whole-house heater is able to provide constant hot water for kitchen and bathroom faucets at the same time. For example, the average flow rate of a water heater in the whole house type should be around 3 to 8 gallons per minute. On the other hand, single-use gallons are fit for smaller families or for people living alone, as they are capable of providing hot water to a single faucet at a time.

You won’t buy a certain water heater just because it is able to heat your water. You will choose one depending on the features it comes with – among the convenient features, you will also have a series of safety features that you have to take into account.

For example, most electric tankless water heaters come with self-protection systems such as freeze protection, temperature lock, self-modulating technology, and so on.

In terms of the warranty, you can get one that protects you from leaks and one for part failure. For example, one of the models we’ve reviewed earlier came with 7 years leakage warranty and with 3 years part warranty.

You have to understand that such a product is going to be used for more than just a couple of years, given the price that they come with. A long – as well as trustful – warranty, can save you a lot of money in repairs and maintenance. As a guideline, remember that the average heat exchanger warranty is usually from ten to 12 years.

Now that you know what you should consider when buying such a product, let’s take a look at some of the most important features and specifications of an electric tankless water heater.

These units can be installed anywhere you want, as long as you have where to plug them in.

You need to wait for a maximum of one minute for your hot water. Naturally, some systems are capable of providing you with instant hot water.

Obviously, an electric system of any kind is always sub-par when compared to its gas counterpart. Thus, electric water heaters require more electricity to operate and the costs may be a little higher as well.

With a tankless system, you will enjoy hot water every single time you open your faucet.

As mentioned above, electric tankless water heaters are believed to use 98% and, in some cases, even up to 99% of the energy they consume in order to heat water.

The fact that a water heater is tankless means that you won’t have a tank full of stagnating water in your house. Such water is susceptible to bacteria build-up.

As with most home appliances, sizing is a very important step in the buying process. If you fail to properly size an appliance, then you will most likely have to return it. The latter process may become quite difficult if you order the product online. Therefore, before buying an electric tankless water heater, you will have to size it for your home’s hot water needs.

To do so, you will need the help of two calculations. Once you know the results, you will have no issue in finding a product that’s perfectly sized for your home and family.

Now, it is time to move on to the actual sizing process, as it follows.

First, you will need to round up your home’s peak demand flow rate. For this, you have to determine when your family uses hot water the most. Most families have their peak demand in the morning when everybody wakes up, showers, shaves, boils coffee, and so on. Keep in mind to calculate the GPM of each hot water appliance that you will use and take the values into account when calculating the peak demand – in short, add them up!

In order to determine the temperature rise, you have to subtract the temperature of the groundwater from the output temperature that you desire. For example, if the temperature of the groundwater is around 50 degrees and you want the output temperature to be 120 degrees, then the temperature rise will be 70 degrees. Calculating this will let you know how powerful the heater should be.

Given that manufacturers actually use Temperature Rise and Flow Rate as terms to advertise their tankless heaters, it will be very easy for you to find the one that fits your needs the best. Just make sure that you calculate the above-mentioned values properly and don’t make any mistakes!

Read our article to learn how water heater heat traps work, too!

In a day-to-day situation, your family will most certainly need hot water to shower and do the dishes in the morning – or in the evening. In this scenario, you need to be able to provide every faucet in your home with instant hot water.

To do so, you will need a so-called whole-house water heater. Such a product is basically a system that meets all your hot water demands for the entire house. However, you have to take into account the size of your home as well. For example, three or four bathrooms will require a large flow type heater, while homes with one bathroom will do just fine with a small flow type.

Single points of application or single rooms will manage just fine with a single-use unit. Just as the name implies, these are small heaters that are perfect for providing a single faucet at a time with hot water. They are efficient, eliminate standby heat loss almost entirely, and are easy to install. For example, you may need up to 4 single-use heaters to meet the hot water demand of a home with three bedrooms.

Portable units are very light and have a significantly smaller flow rate – compared to whole house units, for example. The advantage is that they can be carried and installed wherever you want.
Naturally, such units are ideal for traveling and camping – they can also be installed within an RV.

These are usually installed on the outside wall of the bathroom and come with freeze protection systems. Some units may also feature an enclosure – rain cap – in order to lengthen the service of the product as much as possible. Outdoor heaters are ideal for homes that don’t have enough space available or don’t wish to fill it with a heater.

The Pros and Cons of Electric Tankless Water Heaters

Naturally, electric tankless water heaters come with both pros and cons. Let’s see some of them.

The Costs that Come with an Electric Tankless Water Heater

When it comes to the costs of an electric tankless water heater, you have to take into account the price of the unit itself and then the costs of using and maintaining the product.
Therefore, you will most likely have to deal with the following costs:

Electric tankless models are much cheaper than gas tankless models. However, as mentioned above, they are not cheaper than their tank counterparts. On top of that, given that most electric models are designed for point-of-use, the power they use and their flow rate are not so large in order to justify a bigger cost. As a result, most electric tankless water heaters are under $1000, with an average price of around $600.

On the other hand, the installation, maintenance, and heating costs of an electric tankless water heater are higher than those of gas tankless heaters. This is mainly because, if you are not a professional, you will have to call someone to install your electric heater and then handle its (annual) maintenance. When it comes to heating costs, it is well known that electricity costs more than natural gas – and you will need quite some power to keep an electric tankless water heater running, unlike a gas tankless water heater.

Electric Tankless Water Heaters – Installation & Maintenance

Even though most manufacturers claim that their product is easily installed, it does take more than a couple of screws and a plug to install an electric tankless water heater.
You have to pay attention to what you are doing and follow the user’s guide carefully. Therefore, let’s take a look at how most electric tankless water heaters are installed – it’s not as easy as replacing the salt for water softeners.

Since the installation of an electric tankless water heater will be described in the user’s manual, we decided to provide you with some useful tips rather than tell you how to attach the unit to the wall.

Tankless water heaters can, in fact, accumulate minerals that can then build-up on the heating chamber’s walls and erode them. Therefore, you will have to maintain your tankless heater. You will do so by flushing and removing the mineral deposits within the unit at least once a year. Here’s how to do it:

Learn about how to get rid of air in your how waterline, too.

Frequently Asked Questions

Wrap Up

As you can see, electric tankless water heaters seem to be the ideal solution to on-demand hot water. Since we’ve provided you with some electric tankless water heater reviews, we hope that we’ve been of some help in your journey through these heaters’ world.

On top of that, if you keep in mind everything that we’ve mentioned in our buying guide, you will certainly find some of the best electric tankless water heaters out there. And, after finding them, the last thing for you to do will be to choose the one to fit your needs, your home, and your demand for hot water!

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David is a retired engineer, professional homeowner and a DIY addict. He has been installing home appliances, fixing leaks and doing home improvement projects for the past 30+ years. As an environmentally conscious person, David is extra sensitive to the usage of water resources and consumption of clean and healthy water. He started Water Filter Magazine in order to create an awareness and to share his experience on household water appliances with others .

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